Last week, "WannaCry" took the world by storm, a form of ransomware that targeted 100,000 organizations around the globe. The attack caused Britain's NHS to cancel surgeries and crippled Russian and Chinese private and public institutions.

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In March, Yahoo announced its third breach in less than six months - 32 million users' accounts were unknowingly accessed from 2015 to 2016. The news came just months after the multinational tech company confirmed more than one billion accounts had been infiltrated through a 2013 security breach.

In September, Yahoo revealed a similar attack in 2014 targeted 500 million users.

2. Sony PlayStation Network

In 2011, hacker group Anonymous took down the popular gaming network for 23 days through a DDOS, (distributed denial of service) attack, compromising the data of more than 100 million users.

3. Target

The two-wave attack affected 40 million Target customers in late 2013 and another 70 to 110 million in early 2014.

More than 335,000 people who dined at Arby's between October 2016 and January 2017 had their credit or debit card information stolen, according to a statement from the restaurant chain to KrebsonSecurity.

Arby's discovered the security breach in mid-January, but didn't go public about the incident until February due to an ongoing FBI investigation. Malware was found on payment portals and cash registers at hundreds of locations across the US.

5. InterContinental Hotels Group

InterContinental Hotels Group announced in April that the payment software at more than 1,000 of its hotels were infiltrated by malware from September to December 2016. The incident is part of the same campaign that affected at least 12 hotel restaurants and bars during the same time period.

The malware wasn't "eradicated until the properties were investigated in February and March 2017." However, the company claimed there's no evidence of "unauthorized access to payment card data after December 29, 2016."

The British company said the malware was active from August to December of 2016.